Muffler.



W. J. HEWITT.

MUFFLER,

APPLICATION FILED JULY 27, 1909.-

959,'742. Patented May 31, 1910.

WITNESSES INVENTOR BY 92602946, 74 73. M1011? ATTORNEY UNITED STATES PATENT ormcn.

WILLIAM T. HEWITT, OF SAN FRANCISCO, CALIFORNIA, ASS [GNOR T0 FRANK LB. 'KEEVER, OF SAN FRANCISCO, CALIFORNIA.

' MUFFLER.

Specification of Letters Patent. PatentedMay 31,v 1910.

Application filed July 27, 1909, Serial -No. 509,948.

To all whom it may concern:

' Be it known that 1, WILLIAM J Hnwrrr, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented new and useful Improvements in Mufflers, of which the following is a specification.

The present invention relates to improvements in mufliers for the exhaust from engines and the like,being particularly adapted for use in connection with explosive engines.

The objects of the invention are to more effectually silence the noise of the exhaust and to change said exhaust from intermittent violent expulsions ofthe waste gases to a substantiall continuous and uniform expulsion thereo A furtherjobjectis to provide an apparatus of this character which will increase the efiiciency of thengine by assisting the escape of the waste gases.

In the accompanying drawing, Figure 1 isa longitudinal section of the mutfler; Fig. 2 is a side view of one of the muffler plates; F ig. 3 is an edge .view thereof; Fig 4 is a similar view taken at right anglesto that ofFl.3.

Referring to the drawing, l'g'ijndicates. the casing of the muflier preferablycylindrical in form. The waste gases enter-at one end by an inlet pipe 2 passing through a transverse wall 3, and escape at the other end by a central outlet 4. Within the cylindrical casing, near said latter end, are'arranged a longitudinal series of mufiler plates 5, there the number may be varied-t0 suit the size of theengine and other conditions. Each plate is circular in form so as to'fit tightly within the cylinder 1 and is formed wlth a rectangular opening or slot 6 extending in a general radlal direction to the circumfer; ence of the mufiler from a point near the center. A deflector wall 7 is secured on the back of each plate along one edge 8 of the opening or slot 6, then extending from said Y edge obliquely rearward in a plane making an angie of about-45 degrees with the plane of the plate, as shown at 9, the free edge 10 of the wall bei bent into a plane parallel with the plane 0 the plate and substantially o posite the other longitudinal edge 11 "of t slot or opening 6. The plates of the series are placed in position so that the free edge 11 of the slot of one plate is'in contact with the rear side of the bent outer terminal portion 10 of the deflected wall ofthe plate in front of it, thereby closing the direct passage of the Waste. gases through the opening or slots 6, so that, in order for the waste gases to pass from theopening 6 in one plate to that in the succeeding plate, they must pass around the inner edge of the deflector wall 7 in the space between the two plates to the rear of said 'wall, and then enter and passthrough the opening in the next plate of the series. This arrangement, therefore, compels the gases to travel in a helical path in passing through the series of plates. The

' agranged in an approximately radial direct1on, and therefore transverse to the helical path of the gases. These rifiles consist of channel-shaped strips ofmetal, one side of which is secured to the plate, so that the rifile not only obstructs and retards the passage of\ the gas which is-traveling close to the surface of the plate, but imparts to said gas a rotary or eddying motion, which is gradually transmitted to the entire Volume of gas passing throughthe mufiler. The effect 'is to convert the violent intermittent expulsions. of the gas into a substantially continuous and uniform escape thereof through the outlet passage.

Since each opening in the plates, and each space between the: plates, is always larger than the inside measurement of tlfe diameter of the exhaust pipe from the engine to the muffler, thegas is, at no point of its path, choked or confined inany degree.- Although I may use these mufller lates. alone, without any means other than tiie stroke of the piston in the engine 'to' force the gases through tion'with'suctron fans such as are shown in the United States Letters Patent granted to the muffier, I prefer to use them in combiname September 27, 1904, No'. 771,070. In the drawing, these fans are shown .at 14, mounted upon a shaftj15 driven by a sprocket wh'eel 16 in the manner described in said patent. The revolving fans reduce the back pressure, and cooperate with the mufflers in giving to .the waste gas a helical motion, which it maintains in passing through the mufllers. These muffler-plates give a dc- Cir cided advantage, not only in silencing the noise of the exhaust, but also in reducing the back pressure, even' without the use of the fans. This is shown by the following tests which I have-made on an engine. Nhen exhausting into the atmosphere the engine ran at (370 revolutions per minute; when exhausting through the mufller plates, but with the fans not revolving, the engine ran at 080 revolutions per minute; and when exhausted through the muffler plates with the fans revolving, the engine ran at 750 revolutions per minute. All other conditions were the same.

By the above described arrangement of lnutller'plates with theriitles thereon, there are obtained two advantages. In the first place, the rilllcs intercept and obstruct the llow of the gases between the mulller plates and, by their curved edges, produce eddies in said gases. gases, distributed throughout their entire helical path, between the mulller plates, appear to act as butters or cushions, and prevent excessively violent or explosive ejections of the gases. convert the intermittent explosive and violent expulsions of the gases into a substantially continuous and uniform expulsion thereof, thus ellmlnating the noise caused by such expulsions.

The above described arrangement of the apertured muttler plates and the ritllcs secured thereon not only inultles the expulsion of the gases, but also reduces the back pressure caused by the escape of said gases, and to a corresponding extent increases the power of the engine. This reduction in back pressure appears to be due to the fact that the gases, instead of being expelled into the at.- mosphere through a comparatively short path, are caused to travel a much longer path, namely, the helical path between the mufller plates, while, at the same time, this path does not occupy more longitudinal.

space than an ordinary muliler. This long tortuous path causes the gas to emerge into the atmosphere with a substantially uniform pressure, instead of by a series of violent cxplosions, and the rcsistance'ottered by the atmosphere to the gases when so escaping is less in the formercase than in the latter,

I am aware that it is not new in mutilcrs to cause the as to pass through a tortuous or circuitous path, but in prior forms of mufflers in which this has been done, the gas has been compelled to make sharp turns back upon itself, which cause great friction and loss of power. With my improved mul fler, on the contrary, this extended and tortuous path is obtained without the use of any sharp turns or reversals of direction, and consequently, there is no loss of power in this respect. The advantage in the reduc- These eddying portions of the In other Words, they tion of loss of power from back pressure is therefore due, primarily, to the fact that the waste gases can escape into the atmosphere more easily when escaping under constant pressure than when escaping at greatly varying pressures, and, secondarily, to the means for producing this escape at a substantial, constant pressure without loss of power, which. means are, first the arrangement of the ritllc plates which cause the gas to travel in a long and tortuous path and without any sharp turns or rapid reversal of direction, and, second, the use of the riflies which produce internal, eddies in the gases, which eddies act as cushions or buffers to equalize the pressure in the gases in point of time.

I claim 1. A muttler comprising a casing having an inlet and an outlet, means within the easing forguiding gases in a helical path,between the inlet and the outlet, and devices extending transversely from said means for producing eddies in said gases, substantially as described.- 3

2. A mufller comprising a casing having an inlet and an outlet, a series of apertured mufiler plates between the inlet and the outlet, said mufiler plates being provided with deflecting walls compelling the gases to pass in a circuitous path from the aperture of one mufller plate to that of the next, and a rifile on .each mutlier plate, substantially as described.

3. A muffler comprising a casing having an inlet and an outlet, a series of apertured inutller plates between the inlet and the out let, said mufller plates being provided with deflecting walls compelling the gases to pass in a circuitous path from the aperture of one inutl'ler plate to that of the next, and a ritllc with a curved edge on each mulller plate, substantially as described.

4:. A mutller comprising a casing having an inlet and an outlet, a suction fan in said casing, means within the casing for guiding gases in a helical path between the inlet and the outlet, and devices disposed transversely gases, substantially as described.

A muffler comprising a casing having an inlet and an outlet, a suction fan in said casing, and a series of apertured mutiler plates between the inlet and the outlet, said mutller plates being ,provided with deflecting walls compelling the gases to pass in a circuitous path from the aperture of one mutiier plate to that of the next, substantially as described.

6. A mutller comprising a casing having an inlet and an outlet, a suction fan in said casing, a series of apertured multler plates between the inlet and the outlet, said muiller plates being provided with deflecting walls compelling the gases to pass in acircuitous path from the aperture of one mufiier plate to, that of the next, and a series of riflies to that of the next,.and a series of riflies on' with curved edges on each muflierplate, subeach muflier late, substantially as described; stantially as described. v l

. 7. A' mu er comprising a casing havin- In testimony whereof Ihave hereunto set 6 an inlet and an outlet, a suction fan in sai my hand in the presence of two subscribing 15 casing, a'series of a ertured muiiler plates witnesses. I between the inlet an the outlet, said mufiler WILLIAM J. HEWITT.

'pla'tes being provided with deflecting walls 'Witnesses: r compelling the gases to pass in a circuitousv 'F. M. WRIGHT,

-1 0 path from the aperture of one mufiier plate I D. B. RIoHARns. 

